Fabrication of nano woodpile structure

Woodpile structure which is a simple three-dimensional photonic crystal was fabricated by a two-photon polymerization. Resins with high two-photon absorption cross-section, transparent at near-IR spectral region but highly absorbing around 400 nm, undergo a two-photon absorption and polymerization upon irradiation with 780nm from a Ti:Sapphire femtosecond laser. The mechanical nano-positioning system was adopted to identify the position of the focal point inside the polymer and to fabricate the high resolution nano woodpile structures. The resultant structures have a face-centered-cubic symmetry.